Concentrating pulverulent material



F. ONDRA CONCENTRATING PULVERULENT MATERIAL.

APPLICATION FILED IAN. 2B, 1920- Patented July 4, 1922.

FRAN K ONDRA, OF JOHAN'NESBURG,

TRANSVAAL, SOUTH AFRICA, ASSIGNOR TO CON- CENTRATORS LIMITED, 0]? JOHANNESBURG, TRANSVAAL PROVINCE, SOUTH AFRICA, A COMPANY OF THE TRANSVAAL PROVINCE OF THE UNION OF SOUTH AFRICA.

Specification of Letters Patent.

GONCENTRATING PULVERULENT MATERIAL.

Patented July 4, 1922.

Application filed January 28, 1920. Serial No. 354,646.

To all whom it may concern:

Be it known that FRANK ONDRA, citizen of Czechoslovakia, residing at 17 5 President Street, Johannesburg, Transvaal Province of the Union of South Africa, has invented certain new and useful Improvements in Concentrating Pulverulent Ma terial, of which the following is a specification.

The present invention relates to the gravitational concentration of pulverulent material COIlSiStiIlg of relatively heavy mineral and relatively light gangue.

The principal purpose of the invention is to provide means for concentrating at a small cost large quantities of low grade com minuted ore in such a manner as to give a substantially valueless tailing, and a concentrate sufficiently reduced in bulk to economically reconcentrated by known methods of close concentration. I

The invention is illustrated in the accompanying drawings, in whichig. I is a sectional elevation of apparatus accordin to the invention, and

Fig. II is a front view of the same.

Fig. III is a diagram illustrating the invention.

Accordin to this invention, the whole of the materia is formed with a fluid, into a free jet which is preferably flat and of small thickness and may be projected upwardly at an angle to the horizontal.

Referring to the diagram, Fig, III, the particles progressively fall out of the jet according to their weight and falling tendency. At a given distance from the source 2 of the jet, those gangue particles fall out of which are of diameter x, whilst at the same point mineral particles fall out which are of diameter y, 3/ being of smaller numerical value than m. At a further distance from the source 2 gangue particles of diameter w/a fall out and at the same point gangue particles which may be considered to be of diameter y/a.

The material thus deposited is collected separately from different zones A, B, C, etc., in grades such that the gangue particles in each grade approximate to one size; that is to say, each grade comprises gangue par ticles approximately of size mm and mineral particles of size my where m is a quantity differing in value for each grade. Each grade is then separately sieved through a sieve 9 capable of passing my mineral particles and not passing mm or gangue particles. The large particles of each grade are then discarded.

The two steps, in the order named, of (l) separating by grades according to the falling tendency from the jet, and (2) sep arating each grade by size, are essential to attain the results of this invention. If the first step only is employed each resulting grade does not necessarily differ, in the relative proportions of its gangue and mineral constituents, from the original material. Again, if sieving is resorted to without the first step, mineral particles over-size to the sieve used will be discarded with the gangue, whilst the collected mineral will be eXces sively diluted with small gangue particles which have passed with it through the sieve.

Referring to the drawings, 1 indicates a plane deck which is shown as inclined at an angle of say, forty-five degrees. 2 indicates a nozzle to which fluid is supplied at a uniform rate and pressure from say a steady head tank 3 or other suitable reservoir. The nozzle is arranged near to the bottom of the deck 1 at such an angle as to project a jet of fluid a about parallel with the deck. One nozzle only may be provided, but as a rule, numbers of such nozzles are employed together as indicated in Fig. II, so that the jets from them unite and form a sheet. 5 indicates any suitable form of feeder for passing comminuted material at a uniform and regulatable rate into the jet above the nozzle.

The deck is divided into a number of zones 6 bounded by longitudinal slots 7 formed in the deck at various heights. Below each said slot there may be a slight riffie 8 which does not interfere with the upward movement of the material but which prevents particles from passing over the slot when moving downwardly. The material after passing through the slots is received onto sieves 9 which are of progressively finer mesh the higher they are. Said sieves 9 are hinged to the deck at 10 and are j igged by means of a common connecting rod 11 operated by a cam or eccentric 12. They are inclined downwardly to assist the ready elimination of the gangue material and the inclination can be varied by altering the length of the connecting rod 11, which for this purpose may be extensible at 13. Fluid jets 14: are provided for assisting material to pass through the sieves and 15 indicates a plate which protects the hinge of each sieve.

The carrying fluid may be water or air, the former being preferable for material larger than will pass a 400 mesh screen. A steady pressure oi about 25 lbs. per square inch has been found suitable; this giving the jet a sufiiciently fiat trajectory over a deck of convenient size, say 25 to 30 feet from top to bottom.

The fluid jet effectively separates the individual particles of the material, so allowing the mineral or mineralized particles to dissociate from gangue particles and thus tall freely. Each slot 7 collects the material which "falls in the zone 6 above it. Said material consists of roughly uniformly sized gangue particles, together with mineral particles which on the average are smaller than the gangue particles. Said gangue particles are accordingly eliminated by the sieves 9 whilst the material particles pass through the sieves and are collected. The gangue is discarded in a fairly dry state, the water remaining with the concentrate. This feature is of value when some of the mineral is in very fine particles, since it ensures that none of the mineral is lost. Bet'ore being re-used the water can be run to a settling tank to effect the deposition of such fine mineral particles.

I claim 1. The herein-described process of concentrating pulverulent material in the art of mineral separation which consists in first giving the individual particles an impetus by means of a stream of water under pressure to cause them to travel in a common path at an angle to the vertical; collecting the particles as they fall due to their weights from said path in separate zones progressively spaced alongtheir path of travel to obtain a plurality ofcollections of particles each containing both gangue and mineral particles of substantially the same weight but varying in size according to whether they are gangue or mineral particles; and then separating the particles in each collection according to size to separate the mineral from the gangue particles.

2. The herein-described process of concentrating pulverulent material in the art of mineral separation which consists in first causing the particles to be mixed with a fluid under pressure and to be projected by such pressure in a stream following an uninterrupted path inclined at an angle to the vertical; collecting the particles as they fall due to their weighttrom said stream in prearranged zones to obtain a. plurality of collections of particles each containing both gangue and mineral particles of substantially the same weight but varying as to size; and then separating the particles according to size to separate the mineral from the gangue particles.

3. A concentrator comprising an inclined deck, a nozzle arranged to project a fluid jet substantially parallel with said deck,

means to feed pulverulent matter into the.

jet, the deck being formed with a number ot'transverse slots spaced at different intervals from the jet, and a sieve hinged to the deck beneath each slot, said sieves being or" decreasing mesh away from the nozzle.

FRANK ONDRA. 

